There's A Link Between Your Gut And Mental Health And It *Will* Surprise You

You’re probably familiar with that nervous feeling of “butterflies in the stomach.” Perhaps you’ve experienced a “gut-wrenching” experience when learning of some bad news. Or that knot in your stomach when you’re stressed out. But have you ever thought about what this means, and what may be going on inside your body?

Well, it turns out that our brain and our digestive system are intricately linked. So closely linked, in fact, that some experts say it should be viewed as one system, with the gut often being referred to by scientists as “the second brain.” This link is via the vagus nerve, a direct neuronal connection between the gut and the brain. And the ability of our gut to bidirectionally communicate with the brain, known as the gut–brain axis, is at the forefront of current research.

The gut can be extremely sensitive to emotion. Anger, anxiety, stress, sadness and excitement can all trigger digestive symptoms. When you’re feeling stressed or under extreme pressure, your body can go into “fight-or-flight” mode in anticipation of a perceived threat.

The process of digestion will slow or even stop, so that the body can divert its energy to where it is deemed more important (the muscles and the brain). This is what you may experience before a big presentation or job interview, and can manifest as an unsettled stomach, abdominal pain and other digestive symptoms including diarrhoea.

It has been found that psychotherapies including Cognitive Behavioural Therapy (CBT), relaxation therapy and hypnosis can all provide some relief to patients suffering with functional digestive problems (defined as a digestive problem with no obvious physical cause) such as IBS.

A review of 13 studies showed that in 10 of these studies, patients with digestive issues who tried psychological approaches had a significantly greater improvement in their symptoms to those who received conventional medical treatment.

The role of our gut bacteria

Another huge area of research is examining how the bacteria in our gut (collectively known as the microbiome) is linked to our brain health. The gut contains over 5lb of bacteria (there are thought to be 10x more bacteria than total cells in the body, around 100 trillion!), which play a vital role in our digestive wellness, and this has been well documented.

However, what we are now beginning to discover is that our microbiome can also influence biological functions beyond the gut: affecting things like immunity, metabolism and mental health.

There is growing research that indicates our microbiome can have an impact on how we think, feel and behave, and also on the development of certain neurological conditions. For example, certain strains of bacteria in the gut have been found to secrete the same substances used by our neurons to communicate and regulate mood. These include the neurotransmitters dopamine, serotonin and GABA.

It has been hypothesised that our gut bacteria can influence anxiety and depression. Research at McMaster University in Canada found that disrupting the normal bacterial content of the gut reduced-anxiety-like behavior in mice. This change was accompanied by an increase in brain-derived neurotrophic factor (BDNF), low levels of which have been linked to anxiety and depression. In one study, the gut bacteria from a strain of mice prone to anxious behavior was transplanted into another strain of mice inclined to be calm — and these tranquil mice appeared to become anxious.

Whilst research into how the gut microbiome may influence mental health is still in its infancy, and largely limited to animal studies, it does offer the exciting possibility that addressing digestive health could be part of a multifaceted approach to treating mental health disorders such as anxiety and depression.